US12013242B2ActiveUtilityA1
Method for reading data from inertial sensors
Est. expiryJan 10, 2039(~12.5 yrs left)· nominal 20-yr term from priority
Inventors:Markus Ruf
G06F 18/2113G01C 21/16H04L 7/005G01D 21/00G01C 19/5776
53
PatentIndex Score
0
Cited by
9
References
11
Claims
Abstract
A method for reading data from sensors is disclosed comprising: determining a sequence of measured data over time by means of a sensor, wherein the sequence of measured data over time is generated by step-by-step changes in the measured data at input times, which are determined by an input frequency fa and have a time interval of a period 1/fa of the input frequency; reading output data from the sensor at read times, which are determined by a read frequency fs and have a time interval of a period 1/fs of the read frequency, where the read frequency fs is smaller than the input frequency fa; determining, by means of a low-pass filter of the sensor, the ratio N between the input frequency fa and the read frequency fs from the sequence over time of the numbers of input times lying between two adjacent read times.
Claims
exact text as granted — not AI-modifiedThe invention claimed is:
1. A method for reading data from sensors, comprising:
determining a time sequence of measured data by means of a sensor, wherein the time sequence of measured data is generated by step-by-step changes in the measured data at read-in times, which are determined by a read-in frequency f a and have a time interval of a period duration 1/f a of the read-in frequency;
reading output data from the sensor at read-out times, which are determined by a read-out frequency f s and have a time interval of a period duration 1/f s of the read-out frequency, with the read-out frequency f s being smaller than the read-in frequency f a ;
determining, by means of a low-pass filter of the sensor, the ratio N between the read-in frequency f a and the read-out frequency f s from the time sequence of the numbers of read-in times lying between two adjacent read-out times; wherein
the output data to be read at the read-out times is generated in the sensor by extrapolation of elements of the time sequence of measured data generated before the particular read-out times based on the ratio N between the read-in frequency f a and the read-out frequency f s .
2. The method according to claim 1 , wherein
the period duration of the read-out frequency 1/f s is not a multiple of the period duration of the read-in frequency 1/f a .
3. The method according to claim 1 , wherein
the ratio N is determined by averaging the numbers of read-in times lying between two adjacent read-out times.
4. The method according to claim 1 , wherein
the ratio N is determined by a filter algorithm with a variable time constant; and
the time constant becomes larger in the course of time for determining the ratio N.
5. The method according to claim 1 , wherein
the ratio N in the time increment k after the start of the determination of the ratio N is given by:
N ( k )=(1−2 −q(k) )· N ( k− 1)+2 −q(k) ·n ( k ),
with n(k) being the number of read-in times that have occurred in the time increment k, q(k) being a natural number and N(0)=n(0);
each time increment k has the length of a period duration of the read-out frequency 1/f s ; and
q(k) increases with increasing k.
6. The method according to claim 1 , wherein
the output data is generated according to any one of the following formulas:
Case
I
:
v
(
k
)
=
v
1
(
k
)
·
f
a
·
t
1
r
(
k
)
n
1
(
k
)
+
v
0
(
k
)
·
N
-
f
a
·
t
1
r
(
k
)
n
0
(
k
)
-
v
r
(
k
)
,
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= N;
t 1r (0)= v 1 (0)= v r (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
v 1 ( k+ 1)= v 0 ( k );
for N>f a ·t 1r ((k)+n 0 (k):
v r ( k+ 1)= v 0 ( k )/ n 0 ( k )·( N−f a ·t 1r ( k )− n 0 ( k )); and
t 1r ( k+ 1)=0;
for N≤f a ·t 1r (k)+n 0 (k):
v r ( k+ 1)=0; and
t 1r ( k+ 1)=1/ f a ·( n 0 ( k )+ f a ·t 1r ( k )− N );
Case
I
I
:
for
N
>
f
a
·
(
t
2
r
(
k
)
+
t
1
r
(
k
)
)
:
v
(
k
)
=
v
2
(
k
)
·
f
a
·
t
2
r
(
k
)
n
2
(
k
)
+
v
1
(
k
)
·
f
a
·
t
1
r
(
k
)
n
1
(
k
)
-
v
0
(
k
)
·
N
-
f
a
·
(
t
1
r
(
k
)
+
t
2
r
(
k
)
)
n
0
(
k
)
,
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= n 2 (0)= f a ·t 1r (0)= N;
t 2r (0)= v 1 (0)= v 2 (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
n 2 ( k+ 1)= n 1 ( k );
v 1 ( k+ 1)= v 0 ( k );
v 2 ( k+ 1)= v 1 ( k );
t 1r ( k+ 1)=1/ f a ( n o ( k )− N+f a ·( t 2r ( k )+ t 1r ( k )));
t 2r ( k+ 1)=0;
for N≤f a ·(t 2r (k)+t 1r (k)):
v
(
k
)
=
v
2
(
k
)
·
f
a
·
t
2
r
(
k
)
n
2
(
k
)
+
v
1
(
k
)
·
N
-
f
a
·
t
2
r
(
k
)
n
1
(
k
)
,
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= n 2 (0)= f a ·t 1r =N;
t 2r (0)= v 1 (0)= v 2 (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
n 2 ( k+ 1)= n 1 ( k );
v 1 ( k+ 1)= v 0 ( k );
v 2 ( k+ 1)= v 1 ( k );
t 1r ( k+ 1)= n 0 ( k )/ f a ;
t 2r ( k+ 1)= t 2r ( k )+ t 1r ( k )− N/f a ;
with
v(k) being the output data which are read at the k th read-out time;
n 0 (k) being the number of read-in times positioned between the (k−1) st read-out time and the k th read-out time;
n 1 (k) being the number of read-in times positioned between the (k−2) nd read-out time and the (k−1) st read-out time;
n 2 (k) being the number of read-in times positioned between the (k−3) rd read-out time and the (k−2) nd read-out time;
v 0 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−1) st read-out time and the k th read-out time;
v 1 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−2) nd read-out time and the (k−1) st read-out time;
v 2 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−3) rd read-out time and the (k−2) nd read-out time;
t 1r and t 2r being time intervals; and
v r being a residual term.
7. The method according to claim 1 , wherein,
for the extrapolation of the elements of the time sequence of measured data generated before the particular read-out times, the ratio N determined by means of the low-pass filter in the sensor is controlled to the actual ratio N REF of the read-in frequency f a and readout frequency f s in a control loop; and
the particular result of the control to the actual ratio N REF is used for the extrapolation.
8. The method according to claim 7 , wherein
the control is an I or a PI control;
the control is based on a jump function in N, which jumps from zero to a value greater than zero at a value of N=N REF ; and
in the control, a given positive value y is fed back negatively if the jump function is greater than zero when the actual value of N is present, and the negative given value −y is fed back negatively if the jump function is equal to or less than zero when the actual value of N is present.
9. The method of claim 8 , wherein in case I, the jump function is derived from the number of occurrences of the case N>f a ·t 1r (k)+n 0 (k) in K time increments k i+1 to k i+K , with i and K being natural numbers; and
the output data is generated according to the following formula:
v
(
k
)
=
v
1
(
k
)
·
f
a
·
t
1
r
(
k
)
n
1
(
k
)
+
v
0
(
k
)
·
N
-
f
a
·
t
1
r
(
k
)
n
0
(
k
)
-
v
r
(
k
)
,
Case
I
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= N;
t 1r (0)= v 1 (0)= v r (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
v 1 ( k+ 1)= v 0 ( k );
for N≥f a ·t 1r (k)+n 0 (k):
v r ( k+ 1)= v 0 ( k )/ n 0 ( k )·( N−f a ·t 1r ( k )− n 0 ( k )); and
t 1r ( k+ 1)=0;
for N≤f a ·t 1r (k)+n 0 (k):
v r ( k+ 1)=0; and
t 1r ( k+ 1)=1/ f a ·( n 0 ( k )+ f a ·t 1r ( k )− N ); and
in case II, the jump function is derived from the number of occurrences of the case N>f a ·(t 2r (k)+t 1r (k)) in K time increments k i+1 to k i+K , with i and K being natural numbers, and;
the output data is generated according to the following formula:
for
N
>
f
a
·
(
t
2
r
(
k
)
+
t
1
r
(
k
)
)
:
v
(
k
)
=
v
2
(
k
)
·
f
a
·
t
2
r
(
k
)
n
2
(
k
)
+
v
1
(
k
)
·
f
a
·
t
1
r
(
k
)
n
1
(
k
)
+
v
0
(
k
)
·
N
-
f
a
·
(
t
1
r
(
k
)
+
t
2
r
(
k
)
)
n
0
(
k
)
,
Case
II
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= n 2 (0)= f a ·t 1r (0)= N;
t 2r (0)= v 1 (0)= v 2 (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
n 2 ( k+ 1)= n 1 ( k );
v 1 ( k+ 1)= v 0 ( k );
v 2 ( k+ 1)= v 1 ( k );
t 1r ( k+ 1)=1/ f a ( n o ( k )− N+f a ·( t 2r ( k )+ t 1r ( k )));
t 2r ( k+ 1)=0;
for N≤f a (t 2r (k)+t 1r (k)):
v
(
k
)
=
v
2
(
k
)
·
f
a
·
t
2
r
(
k
)
n
2
(
k
)
+
v
1
(
k
)
·
N
-
f
a
·
t
2
r
(
k
)
n
1
(
k
)
,
wherein the following applies:
initial conditions:
n 0 (0)= n 1 (0)= n 2 (0)= f a ·t 1r =N;
t 2r (0)= v 1 (0)= v 2 (0)=0;
state transitions:
n 1 ( k+ 1)= n 0 ( k );
n 2 ( k+ 1)= n 1 ( k );
v 1 ( k+ 1)= v 0 ( k );
v 2 ( k+ 1)= v 1 ( k );
t 1r ( k+ 1)= n 0 ( k )/ f a ;
t 2r ( k+ 1)= t 2r ( k )+ t 1r ( k )− N/f a ;
with
v(k) being the output data which are read at the k th read-out time;
n 0 (k) being the number of read-in times positioned between the (k−1) st read-out time and the k th read-out time;
n 1 (k) being the number of read-in times positioned between the (k−2) nd read-out time and the (k−1) st read-out time;
n 2 (k) being the number of read-in times positioned between the (k−3) rd read-out time and the (k−2) nd read-out time;
v 0 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−1) st read-out time and the k th read-out time;
v 1 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−2) nd read-out time and the (k−1) st read-out time;
v 2 (k) being the sum of step-by-step changes in the measured data that have taken place at the read-in times that were positioned between the (k−3) rd read-out time and the (k−2) nd read-out time;
t 1r and t 2r being time intervals; and
v r being a residual term.
10. A sensor for measuring measured data, comprising:
a sensor device which is suitable for determining a time sequence of measured data, with the time sequence of measured data being generated by step-by-step changes in the measured data at read-in times which are determined by a read-in frequency f a and a time interval of a period duration 1/f a of the read-in frequency;
a filter which is suitable, upon request from an external device, to output output data at read-out times which is determined by a read-out frequency f s and have a time interval of a period duration 1/f s of the read-out frequency, with the read-out frequency f s being less than the read-in frequency f a ;
a low-pass filter for determining the ratio N between the read-in frequency f a and the read-out frequency f s from the time sequence of the numbers of read-in times lying between two adjacent read-out times; wherein
the output data to be output at the read-out times is generated in the filter by extrapolation of elements of the time sequence of measured data generated before the particular read-out times based on the ratio N between the read-in frequency f a and the read-out frequency f s .
11. An inertial navigation system, comprising:
the sensor according to claim 10 ; and
an evaluation unit which is suitable for requesting the output data at the read-out frequency f s and calculating a navigation solution from this.Cited by (0)
No later patents cite this yet.
References (0)
No backward citations on record.